1. Technical Field
The present invention relates to a light-emitting device.
2. Description of Related Art
As for light-emitting devices in which semiconductor light-emitting elements such as light-emitting diodes “LEDs” are employed, the demands for miniaturization, an increase in high efficiency of light extraction, and high reliability along with an increase in power output have been grown in the markets for backlights, light fixtures, and vehicle lights. In particular, as for side-view type light-emitting devices, demands for high efficiency and high power output, along with reduction in size and thickness, have been intensifying.
As the side-view type light-emitting devices, one device has been disclosed in which light-emitting elements are mounted in a concave portion of a resin package, and light emitted from the opening of the concave portion of the resin package is used as illumination light. In the light-emitting device having the aforementioned constitution, in a case where the height of the opening of the concave portion of the resin package is decreased so as to reduce thickness, a distance between the lateral surface of the light-emitting element and the inner surface of the concave portion of the resin package is shortened, which causes the light having high intensity to be irradiated to the inner lateral surface of the concave portion of the resin package. Accordingly, the resin package is degenerated due to the light from the light-emitting element, which is likely to cause discoloration or cracks. As a result, this leads to reduction in reliability inclusive of the life of the light-emitting device. Also, in the case where the light-emitting element is mounted with solder on the lower surface side of the resin package as a mounting surface, internal stress is generated on the mounting surface and resin on the side opposite to the mounting surface, which is likely to cause the cracks on the upper surface side of the resin package in using the light-emitting element after mounting.
For example, Japanese Unexamined Patent Application Publication No. 2005-5433 A discloses a light semiconductor device “light-emitting device” in which one or plural light-emitting elements, whose shape is square in the case of being viewed from a plane, are arranged in the concave portion of the resin package in the direction that each light-emitting element is rotated about an axis vertical to an arrangement surface at 45 degrees. With this arrangement, the intensity of light from the light-emitting elements, which irradiates to the inner surface of the concave portion of the resin package, can be reduced.